Examples of Dextromethorphan Medications for Adults
For an adult patient, dextromethorphan hydrobromide is available in syrup formulations with standard dosing of 10 mL (containing 30 mg dextromethorphan) every 12 hours, not to exceed 20 mL in 24 hours. 1
Available Formulations
Dextromethorphan polistirex extended-release syrup: Each 5 mL contains dextromethorphan polistirex equivalent to 30 mg dextromethorphan hydrobromide 1
Standard adult dosing: 10 mL every 12 hours, with a maximum of 20 mL in 24 hours 1
The formulation requires shaking the bottle well before use and measurement only with the provided dosing cup 1
Clinical Context for Use
Dextromethorphan is the preferred first-line pharmacological agent for dry cough due to its superior safety profile compared to codeine-based alternatives 2, 3
Maximum cough suppression occurs at 60 mg doses, which is higher than typical over-the-counter preparations, and commonly prescribed doses are often subtherapeutic 2, 4
For optimal therapeutic effect in adults with bothersome cough, doses of 30-60 mg may be needed, with a maximum daily dose of 120 mg 4
Dextromethorphan is a non-sedating opiate that centrally suppresses the cough reflex through modulation of the cough center 2, 3
Important Safety Considerations
Caution is needed with combination preparations that may contain additional ingredients like acetaminophen or other pain relievers, which could lead to inadvertent overdose when using higher dextromethorphan doses 2, 4
Dextromethorphan is primarily metabolized hepatically by CYP2D6, not renally excreted, making it safe for patients with chronic kidney disease without dose adjustment 4
The medication has a better safety profile than codeine or pholcodine, with fewer adverse effects including no risk of physical dependence, constipation, or respiratory depression 2, 5